Given the following code:

#include "stdio.h"

class my_class
{
private:
    my_class() { printf("constructor\n"); }
    ~my_class() { printf("destructor\n"); }
public:
    void hello() { printf("Hello quizful.net!\n"); }
    static my_class& get_instance() {
        static my_class instance;
        return instance;
    }
};

int main( void )
{
    // 1
    return 0;
}

Which of the following fragments will not cause a compilation error when inserted into the string // 1?